Voice Alarm Systems
Voice alarm systems are used in large, complex buildings with large populations, where the safe simultaneous evacuation of all floors has the potential to cause injury due to the movement of large numbers of people under stressful circumstances. In addition to this, the number and width of stairways required in order to achieve simultaneous evacuation would be so great that they would not be financially viable.
In these situations, a strategy for phased evacuation would be implemented, using a voice alarm system, connected to the fire detection and alarm system to evacuate the occupants on the floor of incidence, and to alert occupants to prepare for an evacuation. This is done by automatically playing pre – recorded messages through the system of loudspeakers (as opposed to using the fire alarm sounders)
Examples of typical messages could be:
“EMERGENCY, EMERGENCY, A FIRE HAS BEEN REPORTED PLEASE LEAVE THE BUILDING VIA THE NEAREST AVAILABLE FIRE EXIT. DO NOT USE THE LIFTS.
“ATTENTION PLEASE, ATTENTION PLEASE, WE ARE CURRENTLY INVESTIGATING A REPORTED FIRE. PLEASE PREPARE TO EVACUATE THE BUILDING. DO NOT LEAVE NOW, PLEASE WAIT UNTIL FURTHER ADVISED.”
The link between the Fire detection and alarm control panel and the Voice alarm control panel needs to be secure. It must be monitored for open and short circuits, and must be wired in recognised fire resistant cables
In some circumstances, a site may require a combination on voice alarm loudspeakers and fire alarm sounders. In such cases the operation of the sounders should not affect the intelligibility of the voice alarm system. The sounder tone should be the same as the ‘attention drawing tone’ of the voice alarm system.
There are three methods of providing voice alarm messages, these are:
- Stand alone voice sounders
- Central rack amplifier systems
- Distributed amplifier systems
All of the above have a possible use, dependant on the type and size of the building in question.
